Novel photochrome aptamer switch assay (PHASA) for adaptive binding to aptamers

Vladislav Papper, Oleksandr Pokholenko, Yuanyuan Wu, Yubin Zhou, Ping Jianfeng, Terry W.J. Steele, Robert S. Marks

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


A novel Photochrome-Aptamer Switch Assay (PHASA) for the detection and quantification of small environmentally important molecules such as toxins, explosives, drugs and pollutants, which are difficult to detect using antibodies-based assays with high sensitivity and specificity, has been developed. The assay is based on the conjugation of a particular stilbene-analyte derivative to any aptamer of interest. A unique feature of the stilbene molecule is its reporting power via trans-cis photoisomerisation (from fluorescent trans-isomer to non-fluorescent cis-isomer) upon irradiation with the excitation light. The resulting fluorescence decay rate for the trans-isomer of the stilbene-analyte depends on viscosity and spatial freedom to rotate in the surrounding medium and can be used to indicate the presence of the analyte. Quantification of the assay is achieved by calibration of the fluorescence decay rate for the amount of the tested analyte. Two different formats of PHASA have been recently developed: direct conjugation and adaptive binding. New stilbene-maleimide derivatives used in the adaptive binding format have been prepared and characterised. They demonstrate effective binding to the model thiol compound and to the thiolated Malachite Green aptamer.

Original languageEnglish
Pages (from-to)1581-1591
Number of pages11
JournalJournal of Fluorescence
Issue number6
StatePublished - 1 Jan 2014


  • Aptamer
  • Fluorescence
  • Maleimide
  • Photoisomerisation
  • Stilbene


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